Homebrew Tap with updated OpenSSH for Mac OS X with enhanced smartcard support including ECDSA keys support.
Based on https://raw.githubusercontent.com/Homebrew/homebrew-dupes/master/openssh.rb
To install using OpenSSL:
# brew install mbrossard/homebrew/openssh --with-brewed-openssl
To install using LibreSSL:
# brew install mbrossard/homebrew/openssh --with-brewed-libressl --with-libressl